Effects of Alanine and Glycine Substitution for Tryptophan on the Heterogeneity of Gramicidin A Analogs in Micelles

✍ Scribed by J.F. Hinton; A.M. Washburn-McCain; A. Snow; J. Douglas

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 161 KB
• Volume: 124
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1996.7493

✦ Synopsis

The effects of alanine and glycine substitution for tryptophan upon the species heterogeneity of gramicidin A analogs incorporated into SDS micelles have been investigated. The sequential replacement of the four tryptophan residues in gramicidin A at positions 15, 13, 11, and 9 with glycine showed that there was no detectable effect at position 15 but increasing heterogeneity of species in the micelles proceeding toward the interior of the micelle at position 9. The replacement of tryptophan at positions 15 and 9 with alanine was found to produce more species heterogeneity than found with glycine substitution at the same positions. An increase in the SDS concentration reduces the number of different species present in micelles. With the Gly-11, Gly-13, and Gly-15 analogs, the increase in SDS concentration results in the formation of a single species; however, for the Gly-9, Ala-9, and Ala-15 analogs, heterogeneity remains.